You've got datomic on the server and datascript on the client, transit on the wire, reader conditionals to share code and much more. Plus everything can be modified as its running.
When it comes to web frameworks I don't really care about performance as much as I care about managing complexity. Which is why I'm looking at om.next over all the other frameworks.
And managing complexity is not something you can benchmark in toy projects - every single framework is virtually the same at such a small scale.